I new to the forums and hope someone a little more knowledgable than me can help me out.

I've got a patio door that is leaking at the top. There is a deck directly above the door (actually the deck wraps around the house). Its doesn't appear to be leaking along the full length of the door, just the center 14-20 inches. The water is dripping from the strip of wood along the top that holds the sliding portion of the door in the patio frame. There is also a motion light about 8 inches above the top of the patio door, directly over where the door is leaking. The house is not quite 5 years old.

I was going to spray the siding with the hose this weekend to verify that it was leaking under the deck and not higher up.

Can anyone give me any advice where else I should be looking and what I should be looking for? The builder didn't do the siding (contracted out) so I'm not sure if I should call the builder back out or the siding company. Any advice on that?

Welcome Joe:
The hose will tell the story but I'm wondering if the deck was built before the siding was applied. If that is the case and the light penetrates the siding too, I think you have your culprit. You may need to place a 'Z' flashing over the door; metal would go on top of the frame, extend to the outside and down with a little kick out at the bottom to allow the water to drip off.
Glenn

thanks for the responses. I spend today with the hose and sprinkler and believe that I have determined the source of the leak. It appears that the water is getting behind the siding between the lower portion of the window and the j-channel (hope that is the right term). This window sits above about 10" above the deck and is directly over the patio door.

here is an image (sorry its really rough) of what I'm seeing after pulling some siding off...

The green represents the window, the red is the OSB wall and the purple is the j-channel under the window. I believe the water is getting in between the window and the channel. The siding itself obviously sits between the vertical portion of the channel and the lip of the channel. Looking at this setup, there is nothing to prevent any water that gets between the channel and the window from running down behind the channel and behind the rest of the siding.

When the house was built, they wrapped it in tyvek, so when I actually got the siding off, there was one giant tear in the tyvek which I patched. I assumed the water was getting in there, since the rest of the tyvek should be waterproof. I put everything back together and it still freaking leaks.

Can anyone comment on whether or not my little image is correct? It doens't make any sense to me (I'm an mechanical engineer by trade) to let water get between the window and channel only to let it run down behind the rest of the siding. Is there something missing? The other kicker here, is ALL of my window are exactly the same way. I could have water running in all over the place. UHG, I can feel my blood pressure going up already.

Again, any and all help is greatly appreciate. Tomorrow I'm going to take the siding off again, and the first deck board next to the house. I'll post pictures, hopefully that will give a clearer picture.

90% of the homes built today are exactly as you described, If there is water getting behind the J channel at the window, You need to caulk across the bottom and up each side. just a thin bead of a good exterior siliconized caulking between the window and J.

But more important is the slicker behind the siding. Vinyl siding to me is like a raincoat. If your zipper is open your insides get wet. The barrier behind the siding is your last line of defense, and if installed wrong anywhere, it will leak and cause damage you will not see.
I would remove the siding above the deck, and make sure your tyvek is lapped over each other in the direction the water will not penetrate. I'm sure you understand, it's just alot of work to do it right.
If you have questions, try posting some pictures we can help with. Or get a different siding guy out there to give you real solutions, and point out what someone else did wrong.
Good luck, and let us know what you find.

If siding is done correctly there should never be a need for any caulking. All it's going to do if fail in time and act like a dam to stop water from running out.
One thing I forgot to ask is, is the deck of stoop sitting level with the under side of the slidding door? If so plan on it always leaking into the house. No door way should ever be within 4" min. of and threshold.
Every single year we get to pull out about 4 or 5 doors that were set with no sill pan and are dead level with the threshold and the whole floors rotted out under it. Then you look up and there's no over hang and no gutters so all that waters splashing up on the door.